The aza-ene reaction of heterocyclic ketene aminals with enones: an efficient and simple synthetic route to fused di- and tri-heterocycles
作者:Jian-Heng Zhang、Mei-Xiang Wang、Zhi-Tang Huang
DOI:10.1039/a903356d
日期:——
Heterocyclic ketene aminals bearing a secondary amino moiety acted as hetero-ene components to react with a number of enones under very mild conditions. The reaction of five- and six-membered heterocyclic ketene aminals 5 and 8 with methyl vinyl ketone proceeded effectively through the aza-ene addition, imine–enamine tautomerization and intramolecular cyclization to give good yields of 8-aroyl-5-hydroxy-5-methyl-1
带有仲氨基部分的杂环烯酮缩醛在非常温和的条件下作为杂烯组分与许多烯酮反应。五元和六元杂环烯酮缩醛5和8与甲基乙烯基酮的反应通过氮杂烯加成,亚胺-烯胺互变异构化和分子内环化有效地进行,从而获得了高产率的8-芳基-5-羟基-5-甲基1,2,3,5,6,7-六氢咪唑并[1,2- a ]吡啶6和9-芳酰基-6-羟基-6-甲基-1,2,3,4,7,8-六羟基-6 H-吡啶基[1,2- a]嘧啶9。当甲基乙烯基酮过量存在时,初步形成的产物6进行了第二次氮杂烯反应,然后进行分子内环化和水参与的脱苯甲酰化,生成了类固醇-4,9-二羟基-4,9-二甲基-1,2作为唯一产物,5,6,6a,7,8,10α-八氢-4 H,9 H-咪唑并[1,2,3- ij ] [1,8]萘啶-10α-苯甲酸基乙酯7。在回流的乙腈中,杂环烯酮缩醛5进行了氮杂烯加成和与许多取代的α,β-不饱和酮的环缩合反应,从而得到1,2,3,7-四氢咪唑并[1